Homogeneous Dual Fluorescence Count of CD4 in Clinical HIV-Positive Samples via Parallel Catalytic Hairpin Assembly and Multiple Recognitions

Abstract

Regularly measuring the level of CD4+ cells is necessary for monitoring progression and predicting prognosis in patients suffering from an infection with the human immunodeficiency virus (HIV). However, the current flow cytometry standard detection method is expensive and complicated. A parallel catalytic hairpin assembly (CHA)-assisted fluorescent aptasensor is reported for homogeneous CD4 count by targeting the CD4 protein expressed on the membrane of CD4+ cells. Detection was achieved using CdTe quantum dots (QDs) and methylene blue (MB) as signal reporters. CdTe QDs distinguished CHA-assisted release of Ag + and C−Ag + −C and MB that has differentiated cytosine (C)-rich single-stranded DNA (ssDNA) and C−Ag + −C, generating changes in fluorescence intensity. With the assistance of the CHA strategy and luminescent nanomaterials, this method reached limits of detection of 0.03 fg/mL for the CD4 protein and 0.3 cells/mL for CD4+ cells with linear ranges of 0.1 to 100 fg/mL and 1 to 1000 cells/mL, respectively. The method was validated in 50 clinical whole blood samples consisting of 30 HIV-positive patients, 10 healthy volunteers, and 10 patients with cancer or other chronic infections. The findings from this method were in good agreement with the data from clinical flow cytometry. Due to its sensitivity, affordability, and ease of operation, the current method has demonstrated great potential for routine CD4 counts for the management of HIV, especially in communities and remote areas.

Steric Hindrance-Mediated Enzymatic Reaction Enable Homogeneous Dual Fluorescence Indicators Aptasensing of Hepatocellular Carcinoma CTCs

“…For fluorescence analysis, two targets can simultaneously be detected by employing two luminescent materials without spectral overlapping, after which we called dual fluorescence indicators analysis. , For instance, Ce 3+ can react with PPi to form fluorescent pyrophosphate cerium coordination polymeric nanoparticles (PPi-Ce CPNs), while nucleotide chains can also be identified by some fluorescent dyes. Among them, methylene blue (MB) can specifically react with cytosine (C)-rich single-stranded DNA (ssDNA), which was a product of TdT and dCTP. − On the other hand, the high efficiency of amplification usually brings high background signal and error, especially in trace detection like CTCs. Hence, changing 3′-OH of DNA to 3′-PO 4 , 3′-NH 2 or hiding it by some other groups is a common way to inhibit nonspecific reactions of TdT, which leads to a reduction in the amplification signal …”